At the start of the week you make a ‘pact’ and tell the app how many days a week you want to exercise.

You then 'check in' at the gym using your iPhone - but must stay for 30 minutes.

Every Sunday night money from those who missed sessions is pooled and divided out among those who didn't.

Should you miss any days your credit card is charged a minimum of $5 per day missed. But to incentivise yourself you can pledge as much as you like.

The app’s website says: ‘Every week, we will pay out cash rewards to those who met their Pact from the Stakes paid by people who didn’t quite make it. Rewards can be cashed out via Paypal. We think if you put real money on the line, you should get real rewards.’

If you miss a session due to illness you can ask your doctor or employer to email the app an exemption note.

The concept certainly seems to be working with the maker claiming that 90 per cent of users are fulfilling their pacts.